In a diesel engine, an accumulator fuel injection device in which pumped fuel from a fuel tank is pressurized by a high-pressure supply pump, and in which pressurized fuel is injected from a compression chamber of a common-rail into a combustion chamber via a injector provided in each cylinder, for example, is known as a fuel injection device that is used in an internal combustion engine having a plurality of cylinders.
In the accumulator fuel injection device that includes the injectors provided in each cylinder, the fuel injection quantity that is injected and supplied from the injectors into each combustion chamber may become unstable (fluctuation), and so-called misfire phenomenon that prevents fuels from being ignited may be caused. Therefore, the fluctuation of explosion power in each cylinder or the deterioration of exhaust emission may be caused due to unstable combustion conditions of each cylinder, and as a result, the running performance of the diesel engine may be deteriorated.
For reducing the fluctuation of fuel injection quantities in each cylinder, so-called FCCB control (Fuel Control for Cylinder Balancing) that detects a rotational fluctuation of a crankshaft when the operational state of the diesel engine is in the stable state, and corrects the fuel injection quantity in accordance with the detected rotational fluctuation, is known (for example, refer to a patent document 1).
Further, a combustion diagnosis device for the internal combustion engine that determines the combustion state of the diesel engine in accordance with the correction amount of fuel injection quantity calculated by the FCCB control, is also known.